Republished: Competitive flow diversion of multiple P1 aneurysms: proposed classification.

We report the case of a patient with subarachnoid hemorrhage and three aneurysms arising from the posterior communicating artery (Pcomm)-P1 complex, treated with endovascular coiling and competitive flow diversion. The largest and likely ruptured Pcomm aneurysm was treated with traditional coiling. Two smaller potentially ruptured aneurysms arose from the distal right posterior cerebral artery (PCA) P1 segment. After a failed attempt to treat with conventional flow diversion across the PCA-P1 segment, the P1 aneurysms were successfully treated with competitive flow diversion distal to the PCA-P1 segment from Pcomm to the P2 segment. Over 12 months, competitive flow diversion redirected flow to the right PCA territory via the internal carotid artery-Pcomm-P2, reducing the size of the PCA-P1 segment and obliterating the P1 aneurysms. Competitive flow diversion treatment should be considered for aneurysms occurring at the circle of Willis when traditional methods are not feasible. Herein, we introduce a novel classification for competitive flow diversion treatment.

A Comparative Classification Analysis of Abdominal Aortic Aneurysms by Machine Learning Algorithms.

The objective of this work was to perform image-based classification of abdominal aortic aneurysms (AAA) based on their demographic, geometric, and biomechanical attributes. We retrospectively reviewed existing demographics and abdominal computed tomography angiography images of 100 asymptomatic and 50 symptomatic AAA patients who received an elective or emergent repair, respectively, within 1-6 months of their last follow up. An in-house script developed within the MATLAB computational platform was used to segment the clinical images, calculate 53 descriptors of AAA geometry, and generate volume meshes suitable for finite element analysis (FEA). Using a third party FEA solver, four biomechanical markers were calculated from the wall stress distributions. Eight machine learning algorithms (MLA) were used to develop classification models based on the discriminatory potential of the demographic, geometric, and biomechanical variables. The overall classification performance of the algorithms was assessed by the accuracy, area under the receiver operating characteristic curve (AUC), sensitivity, specificity, and precision of their predictions. The generalized additive model (GAM) was found to have the highest accuracy (87%), AUC (89%), and sensitivity (78%), and the third highest specificity (92%), in classifying the individual AAA as either asymptomatic or symptomatic. The k-nearest neighbor classifier yielded the highest specificity (96%). GAM used seven markers (six geometric and one biomechanical) to develop the classifier. The maximum transverse dimension, the average wall thickness at the maximum diameter, and the spatially averaged wall stress were found to be the most influential markers in the classification analysis. A second classification analysis revealed that using maximum diameter alone results in a lower accuracy (79%) than using GAM with seven geometric and biomechanical markers. We infer from these results that biomechanical and geometric measures by themselves are not sufficient to discriminate adequately between population samples of asymptomatic and symptomatic AAA, whereas MLA offer a statistical approach to stratification of rupture risk by combining demographic, geometric, and biomechanical attributes of patient-specific AAA.

The SAFARI Score to Assess the Risk of Convulsive Seizure During Admission for Aneurysmal Subarachnoid Hemorrhage.

BACKGROUND: Seizure is a significant complication in patients under acute admission for aneurysmal SAH and could result in poor outcomes. Treatment strategies to optimize management will benefit from methods to better identify at-risk patients. OBJECTIVE: To develop and validate a risk score for convulsive seizure during acute admission for SAH. METHODS: A risk score was developed in 1500 patients from a single tertiary hospital and externally validated in 852 patients. Candidate predictors were identified by systematic review of the literature and were included in a backward stepwise logistic regression model with in-hospital seizure as a dependent variable. The risk score was assessed for discrimination using the area under the receiver operator characteristics curve (AUC) and for calibration using a goodness-of-fit test. RESULTS: The SAFARI score, based on 4 items (age ≥ 60 yr, seizure occurrence before hospitalization, ruptured aneurysm in the anterior circulation, and hydrocephalus requiring cerebrospinal fluid diversion), had AUC = 0.77, 95% confidence interval (CI): 0.73-0.82 in the development cohort. The validation cohort had AUC = 0.65, 95% CI 0.56-0.73. A calibrated increase in the risk of seizure was noted with increasing SAFARI score points. CONCLUSION: The SAFARI score is a simple tool that adequately stratified SAH patients according to their risk for seizure using a few readily derived predictor items. It may contribute to a more individualized management of seizure following SAH.

Proposed Parent Vessel Geometry Based Classification of Anterior Communicating Artery-Located Aneurysms.

BACKGROUND AND OBJECTIVES: The present study is focused on correlation of parent vessels and neck diameters with anterior communicating artery (AComA) aneurysmal depth and growth direction. The study principally aims to suggest a new classification of AComA-located aneurysms based on the physical characteristics of parent vessels. METHODS: A retrospective analysis was performed of 155 patients with ruptured AComA-located aneurysms. The percentage of difference between both A1 arteries was measured on computed tomography angiography images and neck locations were determined. Accordingly, AComA-located aneurysms were classified into 2 groups. In both groups, A1 and A2 arteries and neck size diameters were measured and their relation with aneurysmal depth was studied. The aspect ratio was calculated. RESULTS: Eleven patients in which the aneurysm neck originates from the AComA proper with almost equal A1s were classified as the true AComA aneurysm group whereas 144 patients in whom the aneurysm neck originates at the dominant A1 bifurcation into the AComA and A2 with the average difference between both A1s of about 84.44% were classified as the dominant A1-bifurcation group. There is significant correlation between aneurysmal depth and neck diameter in both groups (P ≤ 0.05, P < 0.001). The aspect ratio was calculated as equal to 1.166. CONCLUSIONS: The dominant A1 bifurcation type is the most common type of AComA-located aneurysm. The present classification provides clinical value in understanding how AComA aneurysms grow and behave. It helps to understand the geometry of multilobulated aneurysms such as ruptured blebs locations during treatment procedures respecting the direction of the dominant A1 axis in group II. Multiple anatomic variations of this complex AComA area can clarify future subtypes of these 2 groups. Thus, further investigation of more patients is needed.

Basilar artery perforator aneurysms (BAPAs): review of the literature and classification.

Basilar artery perforator aneurysms (BAPAs) are an uncommon subtype of perforating artery aneurysms, with only 18 published cases since their initial description in 1996 by Ghogawala et al To date, there are only seven published cases of ruptured BAPAs treated using endovascular techniques. Given the rarity of these aneurysms, the natural history and ideal approach to treatment has not been established. We describe a new endovascular approach to treating these aneurysms using staged telescoping stents, summarize all published cases of BAPAs, and present a unique classification system to enable future papers to standardize descriptions.

Performance of language tasks in patients with ruptured aneurysm of the left hemisphere worses in the post-surgical evaluation.

OBJECTIVE: To assess the language and verbal fluency performance in aneurismal SAH pre- and post-surgery in patients caused by an aneurysm of the anterior communicating artery (AcomA), left middle cerebral artery (L-MCA) and left posterior comunicating artery (L-PcomA). METHODS: Assessment in 79 patients with SAH, on two occasions: pre- and post surgical treatment. They were divided into three groups by the aneurysms' location. RESULTS: Deterioration is detected in the performance of all patients during the post-surgical period; L-MCA aneurysm patients displayed a reduction in verbal naming and fluency; L-PcomA patients deteriorated in the written language and fluency tasks. CONCLUSION: After the surgical procedure the patients decreased in various language tasks and these differences in performance being directly related to the location of the aneurysm.

Performance of language tasks in patients with ruptured aneurysm of the left hemisphere worses in the post-surgical evaluation / Avaliação da linguagem em pacientes com hemorragia subaracnóidea aneurismática no hemisfério esquerdo piora após a cirurgia

ABSTRACT Sub-arachnoid hemorrhage (SAH) promotes impairment of upper cortical functions. However, few information is available emphasizing changes in language after aneurismal SAH and aneurysm location influence. Objective To assess the language and verbal fluency performance in aneurismal SAH pre- and post-surgery in patients caused by an aneurysm of the anterior communicating artery (AcomA), left middle cerebral artery (L-MCA) and left posterior comunicating artery (L-PcomA). Methods Assessment in 79 patients with SAH, on two occasions: pre- and post surgical treatment. They were divided into three groups by the aneurysms’ location. Results Deterioration is detected in the performance of all patients during the post-surgical period; L-MCA aneurysm patients displayed a reduction in verbal naming and fluency; L-PcomA patients deteriorated in the written language and fluency tasks. Conclusion After the surgical procedure the patients decreased in various language tasks and these differences in performance being directly related to the location of the aneurysm.

RESUMO Hemorragia subaracnóidea (HSA) proporciona alterações nas altas funções cerebrais. Contudo, há poucos trabalhos enfatizando as alterações da linguagem na HSA aneurismática e a influência da localização do aneurisma. Objetivos Analisar e comparar os desempenhos da linguagem e fluência verbal na HSA nos períodos pré e pós-cirúrgicos nos pacientes com aneurismas da comunicante anterior (AcomA), cerebral média (ACME) e comunicante posterior esquerdas (AcomPE). Métodos A avaliação da linguagem de 79 pacientes com HSA aneurismática foi realizada em duas ocasiões: pré e pós cirurgia. Eles foram divididos em três grupos de acordo com a localização do aneurisma. Resultados Os grupos apresentaram deterioração na avaliação pós-operatória com diferentes características. O grupo da ACME demonstraram deterioração na fluência e nomeação, enquanto o da AcomPE pioraram nos testes de linguagem escrita e fluência. Conclusões Após o tratamento cirúrgico, os pacientes deterioraram em vários itens de linguagem com diferenças relacionadas à localização do aneurisma.

Associated Aneurysms in Infratentorial Arteriovenous Malformations: Role of Aneurysm Size and Comparison with Supratentorial Lesions.

BACKGROUND: The natural history and treatment of brain arteriovenous malformations (AVMs) is the object of ongoing debates and discussions. To capture the entirety of these complex lesions, associated vascular pathologies, such as associated aneurysms (AAs), have to be implemented in future risk stratification models, as they are believed to represent additional risk factors for intracranial hemorrhage. The present study aims to determine AA characteristics in posterior fossa AVMs and to compare with AAs accompanying supratentorial AVMs, with special focus on aneurysm size. METHODS: Patients with cerebral AVMs, treated in our department between 1990 and 2013, were analyzed retrospectively. Only patients with flow-related AAs of the feeding arteries were evaluated. Thus, patients harboring intranidal, venous or remote aneurysms were excluded. RESULTS: Of 485 patients with cerebral AVM, 76 patients harbored an AVM of the posterior fossa. Among those, 22 individuals exhibited a total of 35 AAs (n = 8 patients with multiple AAs). Most common location of AAs was the posterior inferior cerebellar artery (n = 20, 57%) and mean AA diameter was 7.9 mm (SD 5.5). In the subgroup of patients with a single AA, mean aneurysm size in posterior fossa AVMs was with 7.8 mm (SD 6.0; range 2-25 mm) significantly larger than the mean size of AAs with supratentorial AVMs (4.8 mm, SD 3.0; range 2-20 mm; p = 0.048). Intracranial hemorrhage was found in 18 of 22 patients (82%) with infratentorial AVMs, and of these, 11 patients suffered from aneurysm rupture. In 14 patients bearing a single AA, 8 (57%) had sustained hemorrhage from aneurysm rupture. The mean diameter of AAs was as supposed in the ruptured group with 9.8 mm (SD 6.9; range 4-25 mm) significantly larger than in the unruptured AA group exhibiting a mean of 5.0 mm (SD 3.3; range 2-10 mm; p = 0.038). Patients with posterior fossa AVMs and AAs were significantly older as compared to those patients with supratentorial lesions (57.1, SD 12.6 vs. 45.8 years, SD 15.9 years; p = 0.004), which was also evident in the subgroup of patients with single AAs (55.2, SD 11.7 vs. 45.8 years, SD 14.9 years; p = 0.038). CONCLUSIONS: AAs of posterior fossa AVMs are larger in diameter than aneurysms accompanying supratentorial AVMs. AA size influences risk for hemorrhage, which, together with the high number of hemorrhagic events in posterior fossa AVMs, justifies treating these pathologies. The higher age of patients with AVMs of the posterior fossa might be one reason for larger AAs in this cohort, when compared to patients with supratentorial AVMs and AAs.

Reconsidering the logic of World Federation of Neurosurgical Societies grading in patients with severe subarachnoid hemorrhage.

OBJECTIVE: Current data show a favorable outcome in up to 50% of patients with World Federation of Neurosurgical Societies (WFNS) Grade V subarachnoid hemorrhage (SAH) and a rather poor prediction of worst cases. Thus, the usefulness of the current WFNS grading system for identifying the worst scenarios for clinical studies and for making treatment decisions is limited. One reason for this lack of differentiation is the use of "negative" or "silent" diagnostic signs as part of the WFNS Grade V definition. The authors therefore reevaluated the WFNS scale by using "positive" clinical signs and the logic of the Glasgow Coma Scale as a progressive herniation score. METHODS: The authors performed a retrospective analysis of 182 patients with SAH who had poor grades on the WFNS scale. Patients were graded according to the original WFNS scale and additionally according to a modified classification, the WFNS herniation (hWFNS) scale (Grade IV, no clinical signs of herniation; Grade V, clinical signs of herniation). The prediction of poor outcome was compared between these two grading systems. RESULTS: The positive predictive values of Grade V for poor outcome were 74.3% (OR 3.79, 95% CI 1.94-7.54) for WFNS Grade V and 85.7% (OR 8.27, 95% CI 3.78-19.47) for hWFNS Grade V. With respect to mortality, the positive predictive values were 68.3% (OR 3.9, 95% CI 2.01-7.69) for WFNS Grade V and 77.9% (OR 6.22, 95% CI 3.07-13.14) for hWFNS Grade V. CONCLUSIONS: Limiting WFNS Grade V to the positive clinical signs of the Glasgow Coma Scale such as flexion, extension, and pupillary abnormalities instead of including "no motor response" increases the prediction of mortality and poor outcome in patients with severe SAH.

Validation of the Modified Raymond-Roy classification for intracranial aneurysms treated with coil embolization.

BACKGROUND: The Raymond-Roy Occlusion Classification (RROC) qualitatively assesses intracranial aneurysm occlusion following endovascular coil embolization. The Modified Raymond-Roy Classification (MRRC) was developed as a refinement of this classification scheme, and dichotomizes RROC III occlusions into IIIa (opacification within the interstices of the coil mass) and IIIb (opacification between the coil mass and aneurysm wall) closures. METHODS: To demonstrate in an external cohort the predictive accuracy of the MRRC, the records of 326 patients with 345 intracranial aneurysms treated with endovascular coil embolization from January 2007 to December 2013 were retrospectively analyzed. RESULTS: Within this cohort, 84 (24.3%) and 83 aneurysms (24.1%) had MRRC IIIa and IIIb closures, respectively, during initial coil embolization. Progression to complete occlusion was more likely with IIIa than IIIb closures (53.6% vs 19.2%, p≤0.01), while recanalization was more likely with IIIb than IIIa closures (65.1% vs 27.4%, p<0.01). Kaplan-Meier estimates demonstrated a significant difference in the test of equality for progression to complete occlusion (p=0.02) and recurrence (p<0.01) between class IIIa and IIIb distributions. For the entire cohort, male gender (p<0.01), ruptured aneurysm (p=0.04), intraluminal thrombus (p<0.01), and MRRC IIIb closure (p<0.01) were identified as predictors of recanalization. For aneurysms with an initial RROC III occlusion, MRRC IIIa closure was found to be an independent predictor of progression to complete occlusion (p=0.02). CONCLUSIONS: This study confirms that the MRRC enhances the predictive accuracy of the RROC.

An integrated, ontology-driven approach to constructing observational databases for research.

The electronic health record (EHR) contains a diverse set of clinical observations that are captured as part of routine care, but the incomplete, inconsistent, and sometimes incorrect nature of clinical data poses significant impediments for its secondary use in retrospective studies or comparative effectiveness research. In this work, we describe an ontology-driven approach for extracting and analyzing data from the patient record in a longitudinal and continuous manner. We demonstrate how the ontology helps enforce consistent data representation, integrates phenotypes generated through analyses of available clinical data sources, and facilitates subsequent studies to identify clinical predictors for an outcome of interest. Development and evaluation of our approach are described in the context of studying factors that influence intracranial aneurysm (ICA) growth and rupture. We report our experiences in capturing information on 78 individuals with a total of 120 aneurysms. Two example applications related to assessing the relationship between aneurysm size, growth, gene expression modules, and rupture are described. Our work highlights the challenges with respect to data quality, workflow, and analysis of data and its implications toward a learning health system paradigm.

¿Es la carga de trombo y su localización en el saco un factor protector de endofugas tipo II? / Is thrombus load and location a protection factor of type II endoleaks?

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Rupture Resemblance Score (RRS): toward risk stratification of unruptured intracranial aneurysms using hemodynamic-morphological discriminants.

OBJECTIVE: We have previously developed three logistic regression models for discriminating intracranial aneurysm rupture status from 119 aneurysms based on hemodynamic-morphological parameters. In this study we exploit their use as a tool for predicting the risk of rupture of aneurysms with a defined Rupture Resemblance Score (RRS). METHODS: We collected three-dimensional images of 85 consecutive aneurysms, applied the three regression models and compared model performance at predicting rupture status against anecdotal metrics (aneurysm size and aspect ratio). We then reinterpreted the model-predicted probability as RRS, where the higher the score the closer the resemblance to previously known rupture components, and applied the RRS prospectively to four unruptured aneurysms with borderline treatment decisions. RESULTS: All three models yielded excellent sensitivity (0.78-0.83) and specificity (0.78-0.84) at a cutoff score of 50%, whereas aneurysm size and aspect ratio showed poor sensitivities (0.28 and 0.33, respectively). Lowering the cutoff score to 30% improved sensitivity to 0.90. The RRS identified most of the ruptured aneurysms and also some unruptured ones that closely resembled ruptured aneurysms hemodynamically and/or morphologically. The prospective application of the RRS to unruptured aneurysms shows that it could provide additional insights for treatment decisions. CONCLUSIONS: Previous regression models based on hemodynamic-morphological parameters are able to discriminate rupture in a new cohort in the same population. A higher probability of rupture is associated with larger size ratio, lower normalized wall shear stress and higher oscillatory shear index. The RRS could potentially stratify rupture risk and assist in treatment decision-making for unruptured aneurysms.

A novel classification system for autogenous arteriovenous fistula aneurysms in renal access patients.

INTRODUCTION: Arteriovenous fistulae (AVFs) constructed for hemodialysis access are prone to aneurysmal degeneration. This can lead to life-threatening sequelae such as aneurysmal rupture. The literature includes various guidelines on the management of certain aspects of access-related aneurysm formation; however, no classification system exists to guide reporting or prognostication. We aimed to create a universally acceptable classification for these aneurysms and establish guidance about their management. METHODS: We clinically examined, duplex scanned, and photographed all of the autologous arteriovenous fistulae in our local renal failure population in January 2010 in order to categorize morphology. We then followed up the cohort for 2 years prospectively to assess outcomes, primarily of rupture or surgical intervention for bleeding. RESULTS: A total of 344 patients were included (292 currently needling their fistula and 52 with low creatinine clearance awaiting dialysis). In all, 43.5% of dialyzed patients had aneurysmal fistulae. We propose a classification system as follows: type 1a: dilated along the length of the vein; type 1b: postanastomotic aneurysm; type 2a: classic "camel hump"; type 2b: combination of type 2a and 1b; type 3: complex; and type 4: pseudoaneurysm. Six fistulae needed emergency surgery for bleeding in the 2-year follow-up period and 5 of these were type 2 aneurysms. The remaining one was in the nonaneurysmal group, although it had become aneurysmal by the time it bled. CONCLUSION: Type 1 aneurysms are much commoner in patients who have not yet needled their fistula and have a relatively innocuous course although type 1a aneurysms should be monitored for high flow and physiological consequences thereof. Type 2 aneurysms are associated with needling of AVFs. They are at significant risk of rupture and need to be monitored carefully or treated prophylactically.

Natural course of subarachnoid hemorrhage is worse in elderly patients.

UNLABELLED: Aging is a major risk factor for poor outcome in patients with ruptured or unruptured intracranial aneurysms (IA) submitted to treatment. It impairs several physiologic patterns related to cerebrovascular hemodynamics and homeostasis. OBJECTIVE: Evaluate clinical, radiological patterns and prognostic factors of subarachnoid hemorrhage (SAH) patients according to age. METHOD: Three hundred and eighty nine patients with aneurismal SAH from a Brazilian tertiary institution (Hospital do Servidor Público Estadual de São Paulo) were consecutively evaluated from 2002 to 2012 according to Fisher and Hunt Hess classifications and Glasgow Outcome Scale. RESULTS: There was statistically significant association of age with impaired clinical, radiological presentation and outcomes in cases of SAH. CONCLUSION: Natural course of SAH is worse in elderly patients and thus, proper recognition of the profile of such patients and their outcome is necessary to propose standard treatment.

Natural course of subarachnoid hemorrhage is worse in elderly patients / A história natural da hemorragia subaracnóide é pior em pacientes idosos

Aging is a major risk factor for poor outcome in patients with ruptured or unruptured intracranial aneurysms (IA) submitted to treatment. It impairs several physiologic patterns related to cerebrovascular hemodynamics and homeostasis. Objective Evaluate clinical, radiological patterns and prognostic factors of subarachnoid hemorrhage (SAH) patients according to age. Method Three hundred and eighty nine patients with aneurismal SAH from a Brazilian tertiary institution (Hospital do Servidor Público Estadual de São Paulo) were consecutively evaluated from 2002 to 2012 according to Fisher and Hunt Hess classifications and Glasgow Outcome Scale. Results There was statistically significant association of age with impaired clinical, radiological presentation and outcomes in cases of SAH. Conclusion Natural course of SAH is worse in elderly patients and thus, proper recognition of the profile of such patients and their outcome is necessary to propose standard treatment. .

A idade é considerada fator de risco de mau prognóstico em pacientes com aneurismas intracranianos rotos ou não-rotos; com o aumento da idade, ficam prejudicados vários padrões fisiológicos relacionados à hemodinâmica cerebral e homeostase. Objetivo Estudar o quadro clínico, os dados radiológicos e o prognóstico nos pacientes com hemorragia subaracnóide aneurismática em relação à idade. Método Foram avaliados consecutivamente, de 2002 a 2012, 389 pacientes com hemorragia subaracnóide aneurismática oriundos de uma instituição terciária brasileira. Resultados Houve associação da idade com pior quadro clínico, radiológico e prognóstico nos pacientes com hemorragia subaracnóide aneurismática. Conclusão O curso natural da hemorragia subaracnoidea é pior em pacientes idosos. O reconhecimento adequado do perfil desses pacientes e seu prognóstico é importante para estabelecer um tratamento adequado. .

Endovascular treatment of an intracranial aneurysm with a ruptured bleb.

OBJECTIVE: To study the features and approaches of endovascular treatment for intracranial aneurysms with a ruptured bleb. METHODS: This retrospective study was carried out from June 2007 to June 2009 in Jilin University, Jilin, China. Thirty patients with intracranial aneurysms with ruptured blebs were included. The aneurysms were diagnosed by digital subtraction angiography (DSA), and the endovascular treatment was planned according to the relationship between the aneurysm body and the ruptured bleb. The aneurysms were classified into 4 types (type I, II, III, IV) based on the size of the neck of the aneurysm connected with the parent artery, the size of the body of the aneurysm, and the size of the junction formed between the aneurysm and bleb. Endovascular treatment for each type of aneurysm was performed. RESULTS: Type IV aneurysms were the most difficult operation performed, easily resulting in rupture and bleeding during surgery, whereas embolization of a type III aneurysm was relatively simple. Type I and II aneurysms resulted in better prognosis. Statistical analysis showed that the outcome of the treatment of type I and II aneurysms was better than that in type III and IV aneurysms, the outcome of type I, II, and III was better than that in type IV. CONCLUSION: The outcome of the endovascular treatment of an intracranial aneurysm with a ruptured bleb was related to the aneurysm type. Treatment in a type-dependent manner is therefore recommended.

3D shape analysis of intracranial aneurysms using the writhe number as a discriminant for rupture.

Intracranial aneurysms are polymorphic focal arterial dilations, which harbor a variable risk of rupture leading to high morbidity and mortality. Increased detection of incidental aneurysms by non-invasive imaging has created a need for rupture risk stratification tools, in addition to simple aneurysm size, to guide optimal treatment strategy. To this end, shape analysis has emerged as a possible differentiator of rupture likelihood. A novel set of morphological parameters based on the writhe number are introduced here to describe aneurysms and discriminate rupture status. Classification in 117 saccular aneurysms (52 ruptured and 65 unruptured) is based on statistical analysis of writhe number distribution on the aneurysm surface. Aneurysms are analyzed both in isolation and including a portion of their parent vessel. Sidewall and bifurcation aneurysm subtypes were found to be best described by disjoint sets of shape parameters, yielding a morphological dichotomy between the two aneurysm classes. Writhe number analysis results in 86.7% accuracy on sidewall (SW) aneurysms and 71.2% accuracy on bifurcation (BF) aneurysms. This represents a 12% accuracy increase for both subtypes compared to the performance of seven established 2D and 3D indexes. The results support the utility of writhe number aneurysm shape analysis, with potential clinical value in rupture risk stratification.